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Richard,
I think you're right on with your comment. I cobbled up the new muffler onto the old manifold and ran it up to 4000 rpm today. At 1500-1600, the noise level inside the a/c was ~89 db, at 4000 it was 102db. It wasn't any noisier than the burned out Hushpower II, but it wasn't much quieter either. Unfortunately, with the setup I had, I didn't want to run it any harder, but it did seem to work better the faster I ran the engine. It wouldn't be any trouble to neck down the exit from 3" to 2". More on that later...
Mark S.
On Sat, Jan 31, 2009 at 9:09 AM, Richard Sohn <res12@fairpoint.net> wrote:
With the inlet and outlet the same size, I would
not be surprised if it does very little noise reduction, if any. Some tests in
the past have shown that a smaller exit makes a considerable difference in sound
level with moderate loss of power.
FWIW.
Richard Sohn
N2071U
----- Original Message -----
Sent: Saturday, January 31, 2009 8:48
AM
Subject: [FlyRotary] My New DNA
Muffler
Hey Guys,
My new DNA muffler arrived yesterday so I
thought I would post a couple of pictures with some information and first
impressions.
It appears to be very well built, all tig welded, and no
packing to burn out. It weighs just under 5#, which is half of what the
Hushpower II weighs, so if it works, I will have reduced my fwf weight by
5#. To be totally honest, my HPII probably no longer weighs 10# as most
of the innards have long departed the a/c.
The model I purchased
was the Gen II - Collector Series, p/n 1040. It has 3" inlet and 3"
outlet, with a 4" dia. body. Total length is21", body length is
15". Literature says that it is good for 1000 hp, so it may have a
chance of lasting at least 100 hrs on my 3-rotor running for hours at
WOT. We'll have to wait and see on the longevity. I have a decible
meter, so I can take some before and after readings. Cost was $152 with
shipping from Canada.
I'm going out to the airport this morning to see
how well it fits. More on how well it fits & works later...
Mark S.
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